Suspension apparatus for washing machine

ABSTRACT

A suspension apparatus for a washing machine comprises: a connection rod having one end mounted to a body of a washing machine; a damper cap having another end of the connection rod penetratingly installed thereat, and mounted to an outer tub; a damper spring installed in the damper cap; a damper base mounted to the damper cap, sling along an inner circumferential surface of the damper cap, and configured to support the connection rod or the damper spring, and; and extension springs disposed below the damper base, and configured to extend an edge of the damper base to an inner surface of the damper cap, wherein the extension springs have a consecutive circumference. Accordingly, an air gap between the damper base and the damper cap can have a uniform clearance, and lowering of a viscous damping force due to excessive abrasion of a specific part can be prevented.

RELATED APPLICATION

The present invention relates to subject matter contained in priorityKorean Application No. 10-2007-0076581, filed on Jul. 30, 2007, which isherein expressly incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a washing machine, and moreparticularly, to a suspension apparatus for a washing machine capable ofeffectively reducing excessive vibration by maintaining a viscousdamping force even when a washing machine is used for a long time.

2. Description of the Background Art

Generally, a washing machine serves to wash laundry by using a softeningprocess by detergent, a frictional process by water stream occurring aswashing blades rotate, an impact process by washing blades, etc. Byusing a motor as a main driving force, the washing machine performs awashing process, a rinsing process, and a dehydrating process so as towash laundry with using detergent and water. The washing machinecomprises a motor serving as a driving unit, a mechanical part fortransmitting energy to laundry, a controller for controlling washingprocesses, a water supply unit for supplying water, and a water drainunit for discharging water.

The washing machine is largely divided into a cylinder type, an agitatortype, and a pulsator type according to washing methods.

According to the agitator type, an agitator protruding from the centerof an inner tub with a wing shape is rotated in right and leftdirections thus to wash laundry. According to the pulsator type, laundryis washed by using turbulent stream occurring as a disc-shaped pulsatoris rotated. According to the cylinder type, water, detergent, andlaundry are put into a drum having a plurality of protrusions, and thenare rotated with a low speed in a horizontal axis, thereby washinglaundry by an impact occurring as the laundry is lifted and dropped bythe protrusions.

FIG. 1 is a schematic sectional view of a washing machine in accordancewith the related art, and FIG. 2 is a sectional view taken along line‘II-II’ of FIG. 1.

Referring to FIGS. 1 and 2, a washing machine 1 comprises a body or acasing 10 that forms appearance; an outer tub 12 mounted in the casing10; an inner tub 13 mounted in the outer tub 12; a suspension apparatus20 or suspensions each having one end connected to an upper innercircumferential surface of the body or the casing 10, having another endconnected to a lower outer circumferential surface of the outer tub 12,and configured to support the outer tub 12; and a driving unit 15disposed below the outer tub 12, and configured to drive the inner tub13.

Each of the suspensions 20 comprises a damper cap 22 installed below theouter tub 12; a connection rod 21 having one end penetrating the dampercap 22, and another end mounted to the casing 10; a damper spring 23mounted in the damper cap 22, and configured to absorb vibration fromthe outer tub 12; and a damper base 24 installed at a lower opening ofthe damper cap 22, and configured to support the connection rod 21 orthe damper spring 23.

A narrow air gap 26 is formed between the damper cap 22 and the damperbase 24, and extension springs 25 are installed below the damper base24.

The extension springs 25 serve to extend a lower portion of the damperbase 24.

Referring to FIG. 3 showing a bottom surface of the suspension apparatusof FIG. 2, each of the extension springs 25 has both ends separated fromeach other, i.e., a non-consecutive circumference. Here, said both endsseparated from each other are curved. Since a non-consecutive part 25 adoes not come in contact with the damper base 24, the extension spring25 does not consecutively contact a lower portion of the damper base 24.

The suspensions 20 serve to reduce a very large vibration or amplitudeoccurring by a resonance at the time of excessive vibration (i.e., atthe time of starting a dehydration process).

According to a basic vibration reducing mechanism, vibration occurringfrom the inner tub 13 is reduced by a viscous damping force occurring asair is discharged through an air hole (not shown) of the damper cap 22,and by a frictional damping force occurring as the damper cap 22 and thedamper base 24 come into friction with each other. Here, excessivevibration or amplitude is reduced by a viscous damping force.

However, the conventional mechanism has the following problems.

An air gap 26 which allows a reciprocation of the washing machine isformed between the damper cap 22 and the damper base 24. If the washingmachine 1 is used by approximately 1000 cycles, a clearance of the airgap 26 increases to allow a large amount of air to leak through the airgap 26. This causes a viscous damping force to be greatly lowered,thereby not reducing excessive vibration.

Besides, since the driving unit 12 is eccentrically installed from thecenter (C) below the outer tub 2, an initial static deflection of theouter tub 2 is toward the driving unit 12.

Furthermore, when the extension springs 25 are used to prevent the airgap 26 from having an increased clearance, a large amount of air isleaked through non-consecutive parts of the extension springs 25. Thatis, the damper base 24 is not outwardly pushed at the non-consecutiveparts 25 a of the extension springs 25, but has a flat part 24 a. Theflat part 24 a has a larger clearance than any other parts, which causesa large amount of air to be leaked and thus a viscous damping force tobe lowered.

Furthermore, when a lubricant such as grease is deposited onto thesurface of the damper cap 22 so as to prevent friction or interferencebetween the damper cap 22 and the outer tub 12, the lubricant blocks anair hole (not shown) of the damper cap 22. This causes a viscous dampingprocess not to be smoothly performed.

SUMMARY OF THE INVENTION

Therefore, it is a first object of the present invention to provide asuspension apparatus for a washing machine capable of constantlymaintaining an air gap between a damper base and a damper cap by pushingthe damper base in a circumferential direction with a constant force,and capable of reducing lowering of a viscous damping force due toincrease of non-uniform clearance of the air gap, in which extensionsprings having a consecutive shape are mounted below the damper base.

It is a second object of the present invention to provide a suspensionapparatus for a washing machine capable of preventing a large amount ofair leakage due to increase of an air gap between a damper cap and adamper base by mounting a base cap to a lower opening of the damper cap.

It is a third object of the present invention to provide a suspensionapparatus for a washing machine capable of preventing lowering of aviscous damping force occurring as an air hole is blocked by alubricant, by forming an air hole at a base cap rather than at a dampercap.

It is a fourth object of the present invention to provide a suspensionapparatus for a washing machine capable of maintaining an elasticrestoration force of an extension spring for a long time by overlappingsome parts of the extension spring in a longitudinal direction, andcapable of easily mounting the extension spring to a damper base.

It is a fifth object of the present invention to provide a suspensionapparatus for a washing machine capable of constantly maintainingabrasion of a damper base in a circumferential direction by applying anextension spring consecutively contacting the damper base in acircumferential direction, and thus capable of enhancing reliability.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided a suspension apparatus for a washing machine,comprising: a connection rod having one end mounted to a body of awashing machine; a damper cap having another end of the connection rodpenetratingly installed thereat, and mounted to an outer tub; a damperspring installed in the damper cap; a damper base mounted to one end ofthe damper cap, sliding along an inner circumferential surface of thedamper cap, and configured to support the connection rod or the damperspring,; and extension springs disposed below the damper base, andconfigured to extend an edge of the damper base to an inner surface ofthe damper cap, wherein the extension springs have a consecutivecircumference.

According to another aspect, the suspension apparatus for a washingmachine comprises: a connection rod having one end mounted to a body ofa washing machine; a damper cap having another end of the connection rodpenetratingly installed thereat, and mounted to an outer tub; an elasticmeans installed in the damper cap; a damper base mounted to one end ofthe damper cap, and configured to support the connection rod or theelastic means; and extension springs disposed below the damper base, andconfigured to outwardly extend an edge of the damper base, wherein aninterval between the damper cap and the damper base is constantlymaintained in a circumferential direction by the extension springs.

Under the above configuration, abrasion of the damper cap and the damperbase in a circumferential direction can be constantly maintained,lowering of a viscous damping force due to increase of non-uniform airgap can be reduced, and durability can be enhanced.

Here, the extension spring is configured so that some parts thereof canoverlap each other in a longitudinal direction. This causes theextension spring to have a consecutive circumference, and allows allparts of the damper base to be outwardly extended.

The extension spring is mounted to a concaved groove formed at a lowerside of the damper base. The concaved groove formed at a lower innersurface of the damper base serves to stably mount the extension springthereto, and to prevent the extension spring from being separated fromthe damper base while the suspension apparatus is operated.

Here, rather than the concaved groove, a stopper for preventing theextension spring from being separated from the damper base may be formedat a lower portion of the damper base.

Here, a slit for facilitating extension of a lower portion of the damperbase may be formed at a lower portion of the damper base. By forming theslit, a lower portion of the damper base can be easily extended even ifan extension spring having a small elastic restoration force is used.

Both ends of the extension spring are curved toward the center. In orderto enhance convenience for installation, the extension spring is firstlymade to have a reduced size with the curved portions being pressed, andthen is mounted to the damper base.

An air hole for air damping may be formed at the damper cap. The airhole may be formed to be disposed at a high position so that the airhole can be prevented from being blocked by a lubricant such as grease.

The suspension apparatus for a washing machine may further comprise abase cap mounted to a lower side of the damper cap, and configured toreduce a leakage amount of air inside the damper cap. By mounting thebase cap to a lower opening of the damper cap, air leakage through anair gap between the damper cap and the base cap can be completelyprevented. It is preferable to maintain a viscous damping force byforming an air hole at the damper cap.

Preferably, the base cap and the damper cap are coupled to each other bya hook, but are not limited thereto. The base cap and the damper cap maybe coupled to each other by forming a screw thread at a coupling portiontherebetween.

An air hole for air damping may be formed at the base cap.

If air leakage through an air gap is prevented by mounting the base capto the damper cap, a viscous damping process is not smoothly performed,which may cause excessive vibration. In order to prevent the excessivevibration occurrence, an air hole may be formed at the base cap.Alternately, an air hole may be formed at the base cap rather than atthe damper cap, thereby preventing blocking of the air hole due to alubricant such as grease.

According to still another aspect, the suspension apparatus for awashing machine comprises: a connection rod having a predeterminedlength; a damper cap to penetratingly insert a part of the connectionrod at the center thereof; a damper base mounted to one end of thedamper cap, and configured to support the connection rod; and extensionsprings disposed below the damper base, and configured to constantlymaintain an air gap between the damper cap and the damper base, and thusto increase a viscous damping force by air leaked through the air gap.

Here, the extension springs consecutively contact lower side surfaces ofthe damper base. Accordingly, even if a lower portion of the damper basecomes into friction with the damper cap to be abraded, an abrasiondegree of the lower portion is lower than that of any other portions.

A base cap for preventing leakage of air inside the damper cap ismounted below the damper cap. An air hole for a viscosity damping isformed at either the damper cap or the base cap, or at both of them.

Under the above configuration, lowering of a viscous damping force dueto air inside the damper cap is prevented.

In the present invention, the extension spring having a consecutivecircumference is mounted to the damper base, thereby uniformlymaintaining a clearance of an air gap between the damper base and thedamper cap, and preventing lowering of a viscous damping force due toexcessive abrasion of a specific part.

In the present invention, increase of a clearance of an air gap due toabrasion of the damper base slidable with respect to the damper cap isprevented, thereby prolonging the life-span of the suspension apparatusfor a washing machine.

In the present invention, an additional base cap is mounted to anopening of the damper cap, thereby preventing lowering of a viscousdamping force even if an air gap between the damper cap and the damperbase is increased.

The present invention also provides a suspension apparatus for a washingmachine capable of preventing lowering of a viscous damping force byforming an additional air hole at a base cap mounted to a lower side ofa damper cap, in which the air hole of the base cap is prevented frombeing blocked by a lubricant deposited to the damper cap.

The present invention also provides a suspension apparatus for a washingmachine capable of enhancing productivity by forming an extension springso that some parts thereof can overlap each other in a circumferentialdirection or a longitudinal direction, or by forming curved portion atthe extension spring, and capable of maintaining an elastic restorationforce of the extension spring for a long time.

The present invention also provides a suspension apparatus for a washingmachine capable of reducing a large amplitude or noise due to excessivevibration at the time of a dehydration process even when a washingmachine is used for a long time.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a schematic sectional view of a washing machine in accordancewith the related art;

FIG. 2 is a schematic sectional view of a part of a suspension apparatusfor a washing machine in accordance with the related art;

FIG. 3 is a bottom view of the suspension apparatus for a washingmachine of FIG. 2;

FIG. 4 is a schematic sectional view of a suspension apparatus for awashing machine according to one embodiment of the present invention;

FIG. 5 is a perspective view of a damper base of the suspensionapparatus for a washing machine of FIG. 4;

FIGS. 6A to 6C are views respectively showing an extension spring of thesuspension apparatus for a washing machine of FIG. 4;

FIGS. 7A to 7C are views respectively showing an extension spring of asuspension apparatus for a washing machine according to anotherembodiment of the present invention;

FIG. 8 is a sectional view showing a modification example of thesuspension apparatus for a washing machine of FIG. 4;

FIG. 9 is an experimental graph comparing a damping force of theconventional suspension apparatus for a washing machine with a dampingforce of the suspension apparatus for a washing machine of FIG. 4according to the present invention; and

FIGS. 10 and 11 are experimental graphs respectively comparing excessivehorizontal and vertical vibration of the outer tub of the conventionalwashing machine to which the suspension apparatus 20 is applied, withthat of the washing machine of the present invention to which thesuspension apparatus 200 of FIG. 4 is applied.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

Hereinafter, the configuration and operation of a washing machineaccording to one embodiment of the present invention will be explainedin more detail with reference to the attached drawings.

Explanation for well-known configurations or functions will be omitted.And the same reference numerals will be given to the same parts as thoseof the aforementioned configurations, and their detailed explanationwill be omitted.

FIG. 4 is a schematic sectional view of a suspension apparatus for awashing machine according to one embodiment of the present invention,and FIG. 5 is a perspective view of a damper base of the suspensionapparatus for a washing machine of FIG. 4

A washing machine according to the present invention has the sameconfiguration as the conventional washing machine 1 except a suspensionapparatus 200. Therefore, explanation about the same configurationexcept the suspension 200 of the present invention will be omitted.

As shown in FIGS. 4 and 5, the suspension apparatus 200 for a washingmachine according to one embodiment of the present invention comprises:a connection rod 210; a damper cap 220 having one end of the connectionrod 210 penetratingly formed thereat; a damper spring 230 installed inthe damper cap 220; a damper base configured to support one end of theconnection rod 210 penetratingly installed at the damper cap 220;extension springs 260 mounted to a lower side of the damper base 240;and a base cap 250 mounted to a lower side of the damper cap 220.

An upper portion of the damper cap 220 is upwardly extending like a neckof a bottle, and the upwardly extending portion encompasses theconnection rod 210.

The connection rod 210 is positioned inside the damper cap 220 via athrough hole 222 formed at the upper portion of the damper cap 220. Oneend of the through hole 222 is protruding to inside of the damper cap220, thereby constituting a connection rod supporting portion 223 thatencompasses and supports the connection rod 210.

One end of the connection rod 210 is fixed to a connection rod fixingportion 245 of the damper base 240. Preferably, the connection rodfixing portion 245 is protruding from an upper side of the damper base240, and has a predetermined height so as to stably support theconnection rod 210.

A plurality of protrusions 246 are formed on an outer circumferentialsurface of the connection rod fixing portion 245. The plurality ofprotrusions 246 are forcibly inserted into an inner circumferentialsurface of the damper spring 230, thereby stably supporting the damperspring 230.

A lower end of the damper spring 230 is supported by the protrusions 246on the surface of the connection rod fixing portion 245, and an upperend of the damper spring 230 is supported by a spring supporting portion224 formed on an inner surface of the damper cap 220.

At an initial state, i.e., at a state that the washing machine is notprovided with washing water or laundry therein, the damper spring 230preferably maintains a compressed state, and the damper base 240 forsupporting the damper spring 230 is positioned at an inner side of alower end of the damper cap 220. The reason is as follows. Once laundryor washing water is introduced into the inner tub 13 (refer to FIG. 1),the damper spring 230 is extended due to a weight of the laundry orwashing water, and the damper base 240 moves to a lower side of thedamper cap 220. Here, if the damper base 240 is positioned at the end ofthe damper cap 220, laundry, etc. is introduced into the inner tub 13,and the damper base 240 may be completely separated from the damper cap220.

Here, the damper spring 230 is preferably a compression coil spring, butis not limited thereto. As the damper spring 230, any elastic meanshaving an elastic restoration force and configured to absorb orattenuate vibration can be used. For example, a rubber member may beused to connect one end of the connection rod 210 and the connection rodfixing portion 245 of the damper base 240. Also, a rubber pillar (notshown) having a cavity therein may be used as the damper spring 230.When the damper spring 230 is used as an elastic means, one end of theconnection rod 210 disposed in the damper cap 220 is preferably disposedinside the damper spring 230.

An air hole 221 is formed at an upper portion of the damper cap 220,through which a viscous damping process due to air inside the damper cap220 is performed. Between an inner surface of the damper cap 220 and anoutermost circumference of the damper base 240, a minute air gap 223 isformed. A frictional damping process occurs through the air gap 223.

The base cap 250 may be mounted to a lower opening of the damper cap220. The base cap 250 is coupled to the damper cap 220 by a hook (notshown) formed at the damper cap 220 with receiving the damper base 240therein. In order to ensure a sealed state inside the damper cap 220,the damper cap 220 and the base cap 250 may be coupled to each other byforming a screw thread at a coupling portion therebetween.

The damper base 240 will be explained in more detail with reference toFIG. 5.

The connection rod fixing portion 245 connected to one end of theconnection rod 210 is formed above the damper base 240, and theplurality of protrusions 246 are provided on an outer circumferentialsurface of the connection rod fixing portion 245. A spring supportingportion 247 is integrally formed below the connection rod fixing portion245. Preferably, the spring supporting portion 247 is formed in a widedisc shape so as to sufficiently support the damper spring 230.

A skirt portion 243 having an area wider than that of the springsupporting portion 247 is integrally formed below the spring supportingportion 247. Here, the skirt portion 243 is in a thin cylindrical shapehaving a predetermined height, and an air gap 223 is formed between anouter surface of the skirt portion 243 and an inner surface of thedamper cap 220.

A plurality of slits 242 are formed at the skirt portion 243 in a heightdirection, and an extension spring 260 is mounted to an inner surface ofthe skirt portion 243. Here, in order to prevent the extension spring260 from being separated from the skirt portion 243, a concaved groove244 or stopping jaws 241 are formed on an inner surface of the skirtportion 243.

Since the extension spring 260 is mounted to the skirt portion 243 witha diameter decreased than the original diameter, it has an elasticrestoration force to restore the original diameter. Due to the elasticrestoration force, the edge of the damper base 240 is extended to aninner surface of the damper cap 220. That is, the skirt portion 243 ispushed to the damper cap 220 thus to be extended.

Here, the skirt portion 243 can have a large extension degree by havingthe plurality of slits 242. The skirt portion 243 can be outwardlyextended even by the extension spring 260 having a small elasticrestoration force.

Either the stopping jaws 241 or the slits 242, or both the stopping jaws241 and the slits 242 can be formed with consideration of the size ofthe damper base 240, or an elastic force of the extension spring 260,etc.

The extension spring 260 has to be provided with a consecutivecircumference. The extension spring 260 will be explained in more detailwith reference to FIGS. 6 and 7.

FIGS. 6A to 6C are views respectively showing an extension spring of thesuspension apparatus for a washing machine of FIG. 4, and FIGS. 7A to 7Care views respectively showing an extension spring of a suspensionapparatus for a washing machine according to another embodiment of thepresent invention.

When viewed from the front, the extension spring 260 of the suspensionapparatus for a washing machine according to one embodiment of thepresent invention is in a ring shape having a consecutive circumference(refer to FIG. 6B), whereas when viewed from the side, the extensionspring 260 has some parts overlapping each other in a longitudinaldirection (refer to FIG. 6C). That is, the extension spring 260 is woundso that both ends thereof can overlap each other by a predeterminedlength.

Here, curved portions 260 a and 260 b are formed at both ends of theextension spring 260 toward the center of the extension spring 260. Thecurved portions 260 a and 260 b are used to mount the extension spring260 to the damper base 240. When the curved portions 260 a and 260 b arepressed at both sides, a diameter of one side of the extension spring260 is decreased to allow the extension spring 260 to be easily mountedto the damper base 240. Then, when the curved portions 260 a and 260 bare released, the extension spring 260 is restored to the originalstate. At the same time, the skirt portion 243 is outwardly extended.

As shown in FIG. 6A, the extension spring 260 consecutively contactslower side surfaces of the damper base 240, i.e., the skirt portion 243,due to its consecutive circumference. That is, all parts of theextension spring 260 come in contact with the skirt portion 243.Accordingly, the air gap 223 between the damper cap 220 and the damperbase 240 is uniformly maintained in a circumferential direction of theextension spring 260, thereby preventing non-uniform clearance of theair gap 223.

As the extension spring 260 having a consecutive circumference is used,the skirt portion 243 of the damper base 240 is prevented from beingflatly abraded even when coming into friction with an inner surface ofthe damper cap 220.

Unexplained reference numeral ‘211’ denotes one end of the connectionrod 210.

FIGS. 7A to 7C are views respectively showing an extension spring of asuspension apparatus for a washing machine according to anotherembodiment of the present invention.

An extension spring 261 of FIG. 7 has the same shape as the extensionspring 260 of FIG. 6 except that curved portions are not formed at bothends thereof.

When viewed from the front, the extension spring 261 is in a ring shapehaving a consecutive circumference (refer to FIG. 7B), whereas whenviewed from the side, the extension spring 261 has some partsoverlapping each other in a longitudinal direction (refer to FIG. 7C).

The extension spring 261 can maintain its elastic restoration force fora long time due to its overlapping parts, and can be easily mounted tothe skirt portion 243. That is, once the extension spring 261 is held bya user with its central part being pressed, a diameter of one side ofthe extension spring 261 is decreased to allow the extension spring 261to be easily mounted to the skirt portion 243.

The extension spring 261 of FIG. 7 has the same shape as the extensionspring 260 of FIG. 6, except that the curved portions 260 a and 260 bare formed at both ends of the extension spring 260 of FIG. 6.Accordingly, the extension springs 260 and 261 can be fabricated byusing the same molding pattern. More concretely, the extension spring260 of FIG. 6 can be fabricated by a molding pattern of the extensionspring 261 of FIG. 7, and then by forming two curved portions at bothends thereof in a pressing manner, etc. Accordingly, one molding patterncan be used to fabricate two types of extension springs, which enhancesthe productivity.

FIG. 8 is a sectional view showing a modification example of thesuspension apparatus for a washing machine of FIG. 4.

The suspension apparatus 200′ of FIG. 8 is different from the suspensionapparatus 200 of FIG. 4 in that an air hole 251 is formed at a base cap250′.

According to the suspension apparatus 200 of FIG. 4, the base cap 250 ismounted to a lower side of the damper cap 220, but an air hole is notformed at the base cap 250. This allows air leakage through the air gap223 to be prevented, but causes air inside the damper cap 220 to have adifficulty in being discharged out, which can not reduce excessivevibration. In order to solve this problem, the air hole 251 may beformed at the base cap 250′.

The air hole 251 of the base cap 250′ is formed approximately at a lowersurface of the suspension apparatus 200′. Accordingly, even if alubricant such as grease deposited on the damper cap 220 flows down, theair hole 251 is not blocked.

When the air hole 251 is formed at the base cap 250′, it is preferablenot to form the air hole 221 blocked by a lubricant at the damper cap220. However, when a sufficient viscous damping force can not beobtained from the air hole 251 of the base cap 250′, it is effective toform the air hole 221 at the damper cap 220. In this case, in order toprevent the air hole 221 of the damper cap 220 from being blocked by alubricant such as grease, the air hole 221 is formed at an upper side.

In order to reduce excessive vibration of the washing machine by using aviscous damping force occurring from air leakage, either the air hole221 of the damper cap 220 or the air hole 251 of the base cap 250′, orboth of them may be formed. This selection has to be performed in theaspect of vibration with consideration of a capacity of the washingmachine, a rotation speed of the inner tube at the time of a dehydrationprocess, etc.

By using each of the suspension apparatuses 200 and 200′, the air gap223 between the damper cap 220 and each of the dampers bases 250 and250′ can be constantly maintained. This causes a viscous damping forceby air leaked through the air gap 223 to be increased.

In the present invention, a viscous damping force can be enhanced by twotimes or more than that of the conventional suspension apparatus 20(refer to FIG. 1). This allows excessive vibration of the inner tub 13(refer to FIG. 1) to be enhanced by 30% or more than that of theconventional washing machine. Hereinafter, the function of thesuspension apparatus according to one embodiment of the presentinvention will be compared to that of the conventional suspensionapparatus with reference to experimental data.

FIG. 9 shows an experimental graph showing an amplitude (mm) accordingto time (seconds). Referring to FIG. 9, the conventional suspensionapparatus 20 shows a damping factor (ζ) of 0.32, whereas the suspensionapparatus 200 according to one embodiment of the present invention showsa damping factor (ζ) of 0.74. The damping factor (ζ) denotes adecreasing ratio of a function expressed as coordinates or time, whichmay be used to represent an indicator to prevent vibration of an object.

The larger the damping factor is, the more enhanced a damping functionis. Accordingly, it can be inferred that a damping function of thesuspension apparatus 200 according to one embodiment of the presentinvention is enhanced by approximately two times or more than that ofthe conventional suspension apparatus 20.

FIG. 10 is an experimental graph comparing excessive horizontalvibration of the outer tub of the conventional washing machine to whichthe suspension apparatus 20 is applied, with that of the washing machineof the present invention to which the suspension apparatus 200 of FIG. 4is applied. And, FIG. 11 is an experimental graph comparing excessivevertical vibration of the outer tub of the conventional washing machineto which the suspension apparatus 20 is applied, with that of thewashing machine of the present invention to which the suspensionapparatus 200 of FIG. 4 is applied.

Referring to FIG. 10, the horizontal axis of the graph denotesX-directional vibration and Y-directional vibration of an upper portionof the outer tub 12, and X-directional vibration and Y-directionalvibration of a lower portion of the outer tub 12, and the vertical axisdenotes an amplitude (mm). The graph of FIG. 10 shows that all theamplitudes according to each horizontal vibration of the presentinvention were decreased by 1 mm˜8.8 mm than those of the conventionalart.

Referring to FIG. 11, the horizontal axis of the graph denotes eachZ-directional vibration of upper and lower portions of the outer tub 12,and the vertical axis denotes an amplitude (mm). The graph of FIG. 11shows that all the amplitudes according to each vertical vibration ofthe present invention were decreased by 2.5 mm˜2.8 mm than those of theconventional art.

As aforementioned, when the suspension apparatuses 200 and 200′according to the present invention are used, excessive vibration isreduced by approximately 30% to the maximum state than that of theconventional art, and clearance of the air gap can be uniformlymaintained.

So far, the present applicant explained about the suspension apparatusapplied to a washing machine, but the suspension apparatus may also beapplied to various fields such as a washing machine compatible with adrier, a dryer, or a combined washing system.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present invention. The presentteachings can be readily applied to other types of apparatuses. Thisdescription is intended to be illustrative, and not to limit the scopeof the claims. Many alternatives, modifications, and variations will beapparent to those skilled in the art. The features, structures, methods,and other characteristics of the exemplary embodiments described hereinmay be combined in various ways to obtain additional and/or alternativeexemplary embodiments.

As the present features may be embodied in several forms withoutdeparting from the characteristics thereof, it should also be understoodthat the above-described embodiments are not limited by any of thedetails of the foregoing description, unless otherwise specified, butrather should be construed broadly within its scope as defined in theappended claims, and therefore all changes and modifications that fallwithin the metes and bounds of the claims, or equivalents of such metesand bounds are therefore intended to be embraced by the appended claims.

1. A suspension apparatus for a washing machine, comprising: aconnection rod having one end mounted to a body of a washing machine; adamper cap having another end of the connection rod penetratinglyinstalled thereat, and mounted to an outer tub; a damper springinstalled in the damper cap; a damper base mounted to the damper cap,sliding along an inner circumferential surface of the damper cap, andconfigured to support the connection rod or the damper spring and anextension spring disposed below the damper base, and configured toextend an edge of the damper base to an inner surface of the damper cap,wherein the extension springs have a consecutive circumference.
 2. Asuspension apparatus for a washing machine, comprising: a connection rodhaving one end mounted to a body of a washing machine; a damper caphaving another end of the connection rod penetratingly installedthereat, and mounted to an outer tub; an elastic means installed in thedamper cap; a damper base mounted to the damper cap, and configured tosupport the connection rod or the elastic means; and an extension springdisposed below the damper base, and configured to outwardly extend anedge of the damper base, wherein an interval between the damper cap andthe damper base is constantly maintained in a circumferential directionby the extension spring.
 3. The suspension apparatus for a washingmachine of claim 1 or 2, wherein the extension spring is configured sothat some parts thereof can overlap each other.
 4. The suspensionapparatus for a washing machine of claim 3, wherein the extension springis mounted to a concaved groove formed at a lower side of the damperbase.
 5. The suspension apparatus for a washing machine of claim 3,wherein either stopping jaws for preventing separation of the extensionspring or slits for extending a lower side of the damper base, or bothof them are formed at a lower side of the damper base.
 6. The suspensionapparatus for a washing machine of claim 3, wherein the extension springhas both ends curved toward the center.
 7. The suspension apparatus fora washing machine of claim 3, wherein an air hole for air damping isformed at the damper cap.
 8. The suspension apparatus for a washingmachine of claim 1 or 2, further comprising a base cap mounted to alower side of the damper cap, and configured to reduce an amount ofleakage of air inside the damper cap.
 9. The suspension apparatus for awashing machine of claim 8, wherein the base cap and the damper cap arecoupled to each other by a hook.
 10. The suspension apparatus for awashing machine of claim 8, wherein an air hole for air damping isformed at the base cap.
 11. A suspension apparatus for a washingmachine, comprising: a connection rod having a predetermined length; adamper cap to penetratingly insert a part of the connection rod at thecenter thereof; a damper base mounted to one end of the damper cap, andconfigured to support one end of the connection rod; and an extensionspring disposed below the damper base, and configured to constantlymaintain an air gap between the damper cap and the damper base, and thusto increase a viscous damping force by air leaked through the air gap.12. The suspension apparatus for a washing machine of claim 11, whereinthe extension spring consecutively contact lower side surfaces of thedamper base.
 13. The suspension apparatus for a washing machine of claim11 or 12, wherein a base cap for preventing leakage of air inside thedamper cap is mounted below the damper cap.
 14. The suspension apparatusfor a washing machine of claim 13, wherein an air hole for a viscositydamping is formed at either the damper cap or the base cap, or at bothof them.